The present invention relates generally to polymer processing techniques and more particularly to a processing system for sealing power feed-through bushings in high voltage (such as 2300 volts and 4160 volts, for example) laminated bus structures.
When through holes are machined in laminated bus structures, the machined surfaces are not perfectly smooth, and voids occur between the later inserted bushings and the bus side walls. These voids can result either during fabrication or after subsequent mechanical assembly, or movement or heat changes, for example. These voids can cause initial electrical failures or may become partial discharge electrical failures on initially good buses as they deteriorate over time, particularly when salt or other contaminants are introduced.
Voids (from air bubbles or cracks, for example) on the order of about 25 micrometers or more in diameter can create electrical partial discharges and lead to electrical failures. The larger the void and the greater the density of voids, the greater the risk of failure.